TOKYO (AFP) - A strong 6.2-magnitude earthquake hit Japan on Monday, setting buildings in the capital swaying but causing no risk of a tsunami, the country's meteorological agency reported.

National broadcaster NHK said there had been no abnormalities detected at nuclear power plants near the epicentre, which was north of Tokyo, where buildings rocked for upwards of half a minute.

"An earthquake occurred at about 16:23 (0723) today," the Japan Meteorological Agency reported.

"Its focus was in the north of Tochigi prefecture. Its depth is about 10km and its magnitude is estimated at 6.2."